Arming and safety devices for a pyrotechnic chain are already known, in particular from U.S. Pat. No. 3,618,527.
In this type of device, the shaft of the motor passes through the housing. The housing is sealed around the motor shaft by dynamic gaskets that are installed very tightly.
Furthermore, known devices generally make use of brush motors instead of electronic control systems. However brush motors present poor reliability; it is known that the brushes of such motors oxidize easily over time, in particular under conditions of very low pressure, specifically in a vacuum environment.
After long periods without being actuated, the arming element can thus remain jammed because of oxidation of the brushes of its electric motor and/or because of adhesion between the motor shaft and the dynamic gaskets that are for sealing the housing.
In order to avoid the motor shaft jamming, it is necessary to have high driving force. Nowadays, in order to achieve this, devices make use of gear motors with spur gears or wormscrews. Increasing the number of parts nevertheless reduces the reliability of a device. It also increases the dimensions and the weight of the device.
Furthermore, increasing the driving force makes it essential for a torque limiter device to be included in order to handle stroke ends.
Consequently, prior art devices are heavy, not very reliable, and expensive.